Manufacture of magnetite electrodes.



. STATES PATENT o FIoE.

warm-En SEEGE-R, or NU'REMBERG, GERMANY.

mamac'ruan or IMA'GNETITE ELEc'rEonEs.

Io Drawing.

To all'whomitmay concern:

Be it known that I, Dr, WALTER SEEGER, a subject of the German Empire, residing at uremberg, in the Kin dom of Bavaria, Germany, have invente certain new and use 1 Improvements in the Manufacture of v MagnetiteElectrodes; and I do hereby de-- clare the following to be a full, clear, and exact description of the invention, such as 'Wlll enable others skilled in the art to which it 1appertain's to make and use the same.

y invention relates to improvements in a process of producing magnetite electrodes having an excess of ferrous oxid'for use in the electrolysis of chlorids of alkalis. As is well known in the art, when heatin iron in steam magnetite, that is an iron oxid of the com osition Fe O, is obtained, which can be use asan electrode in the electrolysis of chlorids of alkalis. Furthermore also suchiron oxids can be used as anodes in the electrolysis of chlorids of alkaliswhich are obtained by the combustion of iron in a current of oxygen under conditions which cause the production of an excess of ferrous oxid above the formula FeO+Fe O,,=Fe O,. I

have discovered that iron oxid electrodes of a similar character can be obtained the composition of which shows FeO and Fe O, in

various proportions, "beginning from very much Fe'O very little Fe,O up to very little FeO very much Fe O 1f iron is heated in steam at a temperature of about 1000 de rees centigrade. This process is zemarkahle in this respect, that in steam of the'temperature indicated the iron is at first transformed into ferrous oxid which con- 'tains but little ferric oxid, and which is gradually transformed into an iron oxid the composition of which approaches the formula Fe O What is more remarkableis the fact, that the iron oxid which is thus obtained and which, is subject to a considerremains sufiiciently coherent and homogeneous to permit its use as an electrode. The reason for this property of the iron oxids may possibly be und in the fact, that the ferrous oxid becomes soft at the temperature of nearly 1000 degrees centigrade and therefore is more readily sintered. This however does not explain, why the magnetic 02nd of 11011 (Fe OJ WlllCh is obtained from the ferrous oxid or apart therefrom, and which Specification of mu rum.

Application filed January 26, 1912. Serial No. 673,662.

centigrade.

oxids which was practically immaterial.

Patented Nov. 18, 1913.

- melts at a. much higher temperature also becomes homo eneous, so that it can well be used as an e ectrode.

' In the manufacture of electrodes of the character described I may start either from compact or more or less finely divided iron, and add thereto substances which are adapted to render the electrodes more homogeneous. As an addition of this character si-. licic acid is particularly useful which combines with a part of the oxids to form sili; oatesdand'cements and strengthens the comoun p First example: An iron tube the wall of which had a thickness of 2 millimeters, and which had an inner diameter of 8 millimeters was heated 24 hours in a current of steam at a tem erature of 1050 degrees There y the tube was transformed into a perfectly homogeneous tube the inner diameter of which was about 3 millimeters, and the outer diameter of which was also considerably increased. The tube consisted of magnetic oxid of iron (Fe O and an excess of about 7 percentage of ferrous oxid.. When the tube was used as an anode in the electrolysis of chlorids of alkalis, it se arated at first splinters of iron oxids, w ereupon it remained almostunaltered and showed only a slight loss in iron Second example: Pure iron powder was molded together with 4 percentage of silicic acid into a tubular block, and heated in the manner described with reference to the first example. I obtained a homogeneous, nonporous tube which contained 3 percentage surplus ferrous oxid, The oxid was not in any way altered by the electrolysis and its resistance was not excessive for practical purposes, so that the old opinion that for this purpose only pure magnetite can be used is proved to be erroneous. Y

As compared to the old method of manufacturing magnetite electrodes which consists in casting the same from molten magnetite in molds, my'improved method is preferable in this respect, that the extremely high temperatures are avoided, and that the electrode is brought into the desired form by shaping the body of iron at the outset which can be done in a most convenient way.

An important advantage of my rocess consists in the fact, that by heating t e iron wrocess. For examplg In :testimony WhfiI'GO'f i have hereunto seb 1-121 tempezmwlre skewed-as of any 1) position can be obmined which so 1 V 'termined propositions of 1 s0 and. e b weed oi ferrous 01;

Insiead Qf'starting from me'mllic irmb E amount, which um w a raw materiaL 1 may start from such 1 1 the presence 0'5 In at a telnpera-v'ua's oxids as are preduccfii in the course 0i about 10% isgrces centigm 20 if the electrdysi-s o'l an lectrode $hows undesirable excess 0f my hand, n I 1' m" i xerrous 02nd, the electrode can be trans- I DR. 2"! 51.12- 1 SiafiQwEEv.

Witn sses:

F112. LUDWIG Emma, 53mm Mijmm.

fermed into an electrode which contains less lerrous 02116. by agaln heatlm' she same 13 a. cuysanb 0i steam. 

